Method and means for controlling the output of a textile drafting mechanism



Aprll 5, 1966 R. HITEHURST 3,243,853

METHOD AND M S F CONTROLLING THE OUTPUT OF A TEXTILE DRAFTING MECHANISM Filed Dec. 10, 1962 3 Sheets-Sheet 1 INVENTOR: Joe R. WHlTEHLJRST aimmm A TTOE/VE Y5 Apnl 5, 1966 J. R. WHITEHURST 3,243,853

METHOD AND MEANS FOR CONTROLLING THE OUTPUT OF A TEXTILE DRAFTING MECHANISM Filed Dec. 10, 1962 3 Sheets-Sheet 2 Ilill ll ElIII Ill INVENTOR.

J05 12. WHWEHUEST' A T TO ENE VS April 5, 1966 J. R. WHITEHURST METHOD AND MEANS FOR CONTROLLING THE OUTPUT OF A TEXTILE DRAFTING MECHANISM Filed Dec. 10, 1962 Po w 1-2-12 SUPPLY 3 Sheets-Sheet 5 INVENTOR. Joe.- E. Wt-HTEHUEST ahfww United States Patent METHGD AND MEANS FOR CGNTROLLING THE OUTPUT (3F A TEXTELE DRAFTING MEKIHA- NISM Joe R. Whitehurst, Bessemer City, N.C., assignor to Ideal Industries, Ina, Bessemer (Iity, N.C., a corporation of North Carolina Filed Dec. 10, 1962, Ser- No. 243,360 13 Claims. (Cl. 19-240) This invention relates to a novel method and apparatus for controlling the output of textile drafting mechanisms of the type associated with drawing frames and which draft several textile strands and combine them into a single strand or web.

A number of textile plants are now adopting the socalled railway system of producing textile strands in the form of slivers, wherein a group or several slivers are drawn from a like number of carding machines to a single roll section or drafting mechanism of a drawing frame. Heretofore, as far as I know, whenever it has become necessary to stop the operation of any one or more of the carding machines in a series from which slivers are directed to a common drafting mechanism, all such carding machines, as well as the drafting mechanism, had to be stopped simultaneously.

Otherwise, due to the constant speed at which slivers issue from carding machines, the weight of the sliver leaving the drafting mechanism would be reduced substantially in proportion to the number of slivers then :missing compared to the number which are normally being fed to the drafting mechanism. Although various devices are available which will vary the draft in accordance with variations in the mass or density of all the slivers being fed to the drafting mechanism, to my knowledge. there is no known prior method of so controlling the draft of a drafting mechanism as to compensate for the loss of one or more slivers or ends, constituting a fraction or the total number of such ends, being fed to the drafting mechanism.

It is therefore an object of this invention to provide a novel method and means for automatically controlling the desired size or weight of textile material issuing from a drafting mechanism in which a given number of ends are directed to the drafting mechanism, which includes detecting any variation in the number of said ends being fed to said mechanism, and automatically varying the draft imparted to said ends by the drafting mechanism, by varying the speed of at least a pair of drafting rolls, proportional to the detected variations in the number of ends.

It is another object of this invention to provide apparatusfor controlling the angular speed of a pair of front drafting rolls of a drafting mechanism wherein a pair of rear drafting rolls is driven at a constant speed, which apparatus comprises means for sensing or detecting the presence or absence of each of a plurality of strands of textile material, such as slivers, in their course to the rear drafting rolls, with means operatively associated with said sensing means for automatically proportionally reducing the speed of the front rolls in response to the sensing of the absence of one or more strands constituting a fraction of the total number of such strands, and which operative means proportionally increases the speed of the front rolls upon restoration of the previously absent strand or strands being sensed by said sensing means.

In its preferred embodiment, the apparatus for can ing out the novel method comprises a plurality of constantly driven power transmission devices connected to a front pair of drafting rolls of a drafting mechanism, each power transmission device including electromag- 3,243,853 Pate d pr. 966

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netically operated clutch means, the actuation of which is determined by the number of strands passing through the rear drafting rolls. When the programmed or proper number of strands are passing through the rear drafting rolls, one of the clutch means is active, and the others are inactive, to effect normal, high speed rotation of the front drafting rolls. Each clutch means, when actuated, effects a predetermined different angular speed to the front rolls than the other, then inactive clutch means, and the particular clutch means which is actuated is determined by numerical variations in strands passing through the rear drafting rolls as sensed by sensing means located adjacent the rear drafting rolls. In the present embodiment, the usual sliver spoons of a drawing frame serve as the sensing means and effect variation in electrical magnitude, the extents of such variation in magnitude serving to select the clutch means which is to be rendered active while rendering inactive the other clutch means,

Some of the objects of the invention having been stated, other objects will appear as the description proceeds, when taken in connection with the accompanying drawings, in which- FIGURE 1 is a somewhat schematic perspective view of the essential elements of a drawing frame, omitting the driving connections between the front bottom drafting roll, the calendar rolls and the coiler mechanism for purposes of clarity, and illustrating a preferred embodiment of the control apparatus of ciation therewitln' FIGURE 2 is an enlarged longitudinal sectional view through the adjustable drive pulley associated with one of the transmission devices and being taken substantially aiong line 22 in FIGURE 1;

FIGURE 3 is a somewhat schematic side elevation of the coiler mechanism showing the driving connection be tween the front bottom drafting roll, the calendar rolls and the coiler mechanism;

FIGURE 4 is an enlarged fragmentary longitudinalsectional view taken substantially along line 4-4 in FIGURE 1 and showing one of the driven pulleys of the transmission devices with the associated electromagnetic clutch;

FIGURE 5 is a schematic electrical diagram of the control circuit for the apparatus of FIGURE 1. I

Referring more specifically to the drawings, with par ticular reference to FIGURE 1, a group of individual slivers is drawn forwardly through a drafting mechanism or common roll section comprising a series of substan: tially parallel and spaced pairs of drafting rolls, the lower or bottom rolls of which are indicated at 11-14, and the upper of top rolls of which are indicated at 21-24. The

drafting rolls 11, 21 are generally known as the No. 4 or back rolls, the drafting rolls 12, 22 and 13, 23 are generally known as No. 3 and No. 2 or intermediate drafting rolls and the drafting rolls 14, 24 are generally known as No. 1 or front drafting rolls. Although all the drafting rolls 1144, 2124 are shown in the forin of fluted rolls, as is desirable, it is apparent that theupper drafting rolls 21, 24, atleast, may be of the smooth-faced or cushion type, without departing from the spirit of the invention.

The group of slivers, in this instance, includes eight individual strands or slivers indicated at 8-1 through.

the present invention in asso other sliver producing or feeding machines in the series feed the slivers S-1 through S8 at the same linear speed.

In their course to the back pair of drafting rolls 11, 21, the textile slivers or strands S-l through S8 pass through a suitable fixed sliver guide 25 and then move against the upper surfaces of respective sliver spoons D-1 through D-8. Hooked medial portions of spoons D-1 through D-8 are pivotally supported on a stationary upper transverse bar 27. The lower rear portions of sliver spoons D-l through D-S are normally held out of engagement with a lower transverse bar 28 as long as their upward forward portions are engaged and held in such position by the moving strands S1 through S8.

However, upon the parting of any one of the slivers, the corresponding spoon pivots about the upper transverse bar 27 and its overbalanced lower, rear portion comes to rest against the lower transverse bar 28. Accordingly, the sliver spoons D1 through D-S are utilized in the present instance as individual sensing or detecting elements for detecting the absence of each strand S-l through S8 being fed to the back pair of drafting rolls 11, 21, although it is apparent that sensing elements independently of the spoons D-l through D8 may be used for the intended purpose, without departing from the spirit of the invention.

Since the sliver spoons D-l through D-.3 serve as the sliver sensing elements in this instance and they are made from electrically conductive material or metal, the transverse bars 27, 28 serve as electrical contact bars or electrodes. However, since the dropping of the rear lower portion of each spoon or sensing element D-1 through D-B against the lower transverse bar 28, due to the parting of a corresponding strand, must effect an individual switching operation independent of any other spoons whose rear lower portions may then be in engagement with the lower transversebar 28, for purposes to be later described, it will be observed in FIGURE that the transverse bars 27, 28 are divided into a plurality of metallic or electrically conductive segments or contacts respectively designated at 32, 33 and which are separated by respective segments of insulation material indicated at 34, 35. The electrical circuit associated with the transverse bars 27, 28 will be later described.

The bottom drafting rolls 11-14 are driven at progressively increasing speeds from the rear roll 11 to the front bottom roll 14, and the top rolls 21-24 are driven by engagement with the respective bottom rolls 11-44 or by the textile material passing therebetween, as is usual. The slivers S1 through S8 are thus drafted in their course from the rear to the front drafting rolls and then extended forwardly and downwardly and are condensed in a conventional trumpet 37 which condenses the slivers S-1 through S8 into a single composite sliver S which is generally of substantially the same weight per unit length as that of each of the individual strands or slivers S-l through S8 as it approaches the rear pair of drafting rolls 11, 21.

Trumpet 37 directs the condensed sliver S to and between a pair of calender rolls 40, 41 which are driven at a slightly greater peripheral speed than that of the front drafting rolls 14, 24. Calender rolls 40, 41 may be of the type which form parts of the coiler mechanism or, as shown in the present drawings, they may be positioned immediately above an inclined coiler tube 42 of a coiler mechanism broadly designated at 43.

Coiler tube 42 is generally termed as a tube gear since its lower portion is integral with a gear 44 driven to rotate about a substantially vertical axis which substantially corresponds to the axis of the open upper end of the inclined tube 42. The condensed sliver S is thus condensed and coiled into a coiler can 45, only the upper portion of which is shown in FIGURE 3.

The drive mechanism between the bottom front drafting roll 14, the calender rolls 4t), 41 and the coiler mechanism 43 may be conventional and, accordingly, will now be described.

Referring to FIGURE 3, it will be observed that the bottom drafting roll 14 has a shaft 50 fixed thereto on which a gear 51 is suitably secured. Gear 51 meshes with a relatively large gear 52 which has a somewhat smaller gear 53 fixed in axial relation thereto and meshing with a gear 54 fixed on a jack shaft 55. A gear 56 meshes with gear 54 and with another gear 57 fixed on the corresponding end of back calender roll 49. A gear 58, somewhat smaller than gear 57, is also fixed on the corresponding end of back calender roll 40 and meshes with a gear 59 fixed on the corresponding end of the front calender roll 41.

Gears 52, 53 are usually in the form of change gears so that the speed of calender rolls 40, 41 may be varied with respect to the bottom drafting roll 14. In the drafting of cotton, for example, it has been found desirable to rotate the calender rolls 40, 41 at a peripheral speed approximately 1.04 times greater than the peripheral speed of the front drafting rolls 14, 24, thus producing a slight draft known as a tension draft in the textile material as it passes from front drafting rolls 14, 24 to calender rolls 40, 41.

It is thus seen that calender rolls 40, 41 always rotate at a peripheral speed having a fixed ratio with respect to the peripheral speed of front drafting rolls 14, 24. The coiler mechanism 43 is also driven in fixed timed relationship to the front drafting rolls 14, 24. To this end, it will be observed in FIGURE 3 that jack shaft 55 has a bevel gear 62 fixed thereon which meshes with a bevel gear 63 on the upper end of a substantially vertically disposed shaft 64. The lower end of shaft 64 transmits rotation to the usual coiler table, not shown, in a manner well known in the art. The tube gear 44 is engaged by a gear 65 fixed on the vertically disposed shaft 64 beneath bevel gear 63.

The relative speeds of the rear and No. 3 pairs of drafting rolls 11, 21 and 12, 22 and the relative speeds between the front and No. 2 pairs of drafting rolls 14, 24 and 13, 23 may also be effected in a conventional manner. In this instance, reduced corresponding ends of the bottom drafting rolls 11, 12, 13, 14 have respective gears 71-74 fixed thereon. All the gears 71-74 are spaced apart from each other. The gears 71, 72 and 73, 74 have respective pairs of change gears 75, 76 and 77, 78 interposed therebetween. Gears 71-74 engage only the respective gears 75-78. The gears 75, 76 rotate in fixed relationship, and gears 77, 78 rotate in fixed relationship. The relative speeds of the bottom drafting rolls 11, 12 and 13, 14 may be varied by replacing the change gears 75, 76 and 77, 78, respectively, with gears of other sizes, as is well known.

In conventional drawing frames, the front bottom roll 14 is usually driven from the main drive of the machine at a constant speed, and the front drafting roll 14 transmits rotation to the second bottom drafting roll 13 substantially in the manner heretofore described. The third bottom drafting roll 12 also transmits rotation to the rear or fourth bottom drafting roll 11 by means substantially as described.

- The second bottom drafting roll 13 transmits rotation to the third bottom drafting roll 12, on conventional drawing frames, through the medium of change gears which are generally termed as crown gears. However, in order to compensate for the loss or absence of one or more strands or slivers Sl through S8 being fed to the drafting mechanism, according to the present method, the conventional crown gears are omitted and the apparatus of the present invention, to be presently described, is substituted for the crown gears. Accordingly, a main drive shaft 80 is suitably journaled on the frame of the drawing frame and is operatively connected to the bottom drafting roll 11 through the medium of a pair of pulleys 8 81, 82 about which an endless V-belt 83 is entrained. Pulley 81 is fixed on drive shaft 80 and pulley 82 is fixed on a shaft 84 extending from the end of back bottom drafting roll 11 opposite from gear 71.

Drive shaft 80 may be driven -by any suitable means and, in this instance, the outer end of drive shaft 80 has a pulley 85 fixed thereon which is engaged by an endless belt 86 which also engages a pulley 87 of an electric motor 99. As shown in FIGURE 5, electric motor 90 has lead wires or conductors 91, 92, 93 extending therefrom which are adapted to be connected to a suitable source of electrical energy or alternating current, not shown.

The main drive shaft 80 is connected to the shaft 50 of bottom front drafting roll 14 through the medium of a plurality of transmission units which are operative, one at a time, according to variations in the number of strands or slivers being properly directed through the drafting mechanism. As illustrated in FIGURES 1 and of the drawings, three such transmission units are provided for connecting main drive shaft 80 to bottom front roll shaft 50 and are generally designated at 95, 96, 97. As will be later described more in detail, the transmission unit 95 transmits rotation from shaft 80 to shaft 50 at the highest predetermined speed when all of the desired number of slivers are being properly fed to the drafting mechanism. Upon the loss or absence of any one of the strands or slivers S-1 through 8-? being detected by one of the sliver spoons or sensing elements D-1' through D-S, the transmission unit 95 is rendered inoperative and transmission unit 96 becomes operative to transmit rotation from shaft 80 to shaft 50 at a slower speed than that which is transmitted by the transmission unit 95 and at a speed which is proportional to the number of slivers remaining intact as compared to the original number of slivers which should be fed to the drafting mechanism.

Upon the absence of any two of the slivers S'1 through S-S being detected by a corresponding pair of the sliver spoons or sensing elements D-l through D-S, such as by the parting of said two slivers, transmission unit 96 is then rendered inoperative, transmission unit 95 remains inoperative, and transmission unit 97 is rendered opera: tive to then transmit rotation from shaft 80 to shaft 50 at a still slower speed than that which is transmitted by the transmission unit 96.

When transmission unit 97 is rendered operative, it transmits rotation to the shaft 59 so that the speed of front bottom roll 14 is proportionally slower than that imparted thereto by the transmission unit 95 in accordance with the number of slivers S-1 through S-8- which then remain intact as compared to the original number of strands or slivers which should be fed to the drafting mechanism when two such slivers are absent. From the foregoing, it is apparent that the so-called crown draft between the two intermediate pairs of drafting rolls 12, 22 and 13, 23 is constant as long as the desired number of slivers are being fed to the drafting mechanism and is proportionally reduced in accordance with any decrease.

in the number of such slivers relative to the total number which should be fed thereto. Thus, the sliver S being formed is of substantially uniform weight per unit length at all times.

In the illustrated embodiment of the invention, each transmission unit 95, 96, 97 comprises an adjustable pitch V-pulley 100 (FIGURES l and 2) which is fixed on main drive shaft 80 and is engaged by an endless V-belt 101. Each V-belt 101 also engages a corresponding V-pulley 102 which is journaled or loosely mounted on the shaft 50 extending from front bottom drafting roll 14 (FIGURES l and 4). Each V-pulley -2 is adapted to be independently coupled or secured in fixed relation to shaft through the medium of an electrically operable or electromagnetic clutch broadly designated at 103. A suitable belt tensioning device may be provided between 6 each pair of pulleys 100, 102 for maintaining the belts 101 under tension, but since such tensioning device forms no part of the present invention, it is not illustrated or described herein.

Although the pulleys 100, 102 and belts 101 are shown in FIGURE/1, it is apparent that suitable gears may be substituted for the pulleys 100, 102 with suitable change gears being substituted for the corresponding belts 101 therebetween, without departing from the spirit of the invention.

In the disclosed embodiment, all the pulleys 100 and 81 mounted on drive shaft are preferably of the adjustable type so that the peripheral speed of back drafting rolls 11, 21 may be adjusted in accordance with the linear speed at which the slivers S-l through 8-8 are fed to the drafting mechanism and so that the different speeds imparted to the front bottom drafting roll 14 by the transmission units 95, 96, 97 may be accurately determined vin accordance with the number of slivers passing through the drafting mechanism, the desired crown draft, and the characteristics of the particular textile material being drafted.

By way of example, a detailed illustration of one of the adjustable pulleys is shown in FIGURE 2. Ad-

' justable pulley 81 may also be constructed in the same manner as the pulley shown in FIGURE 2. Each pulley 100 includes a pair of flanges or cones 104, 105 be tween which the corresponding belt 101 is positioned. Flange 104 has an elongate hub 106 integral therewith and keyed on shaft 80, as at 107. Hub 106 may also be secured to shaft 80 by means of a set screw 110. Hub 105 is externally threaded and has a hub portion 111 of flange 105 threaded thereon which may be locked in the desired adjusted position by a lock nut 112 threaded on the hub 106 of flange 104.

As heretofore stated, each V-pulley 102 is adapted to be coupled to shaft 50 upon actuation of the corresponding electromagnetic clutch 103. Since all the clutches 103 may be identical, only one of them is shown in detail in FIGURE 4. Also, since various types of clutches may be used for the intended purpose, the clutch is shown in FIGURE 4 by way of illustration only, as being of a type such as is manufactured by Stearns Electric Corporation, Milwaukee 2, Wisconsin under their number 7 5.5 SMR and as illustrated on their drawing No. C3105-J,

dated May 17, 1961.

In this instance, each clutch 103 comprises a stator or housing 115 which loosely encircles shaft 50 and Within which the hub 116 of a driven rotor 117 is also loosely positioned so the rotor 117 and its hub 116 may rotate relative to stator 115. Accordingly, a suitable bearing 120 is provided between stator 115 and hub 116. In order to prevent rotation of stator 115, it is fixed to a bracket 121 which may be suitably secured to any fixed part of the machine, such as a portion of the frame of the drawing frame indicated at F in FIGURE 4. The driven rotor 117 is encircled by a magnetic coil 123 fixed to driven rotor 117.

Since the clutch 103 shown in FIGURE 4 is that clutch associated with transmission unit 95 of FIGURE 1, the stator 115 thereof has a pair of electrical conductors or wires a, a1 suitably connected thereto and which extend into the stator 115 and may be suitably connected to the opposed ends of the coil 123. The other two clutches 103, associated with transmission units 96, 97, have respective conductors b, b-1 and c, c-l connected thereto which correspond to the conductors a, a-l. In this instance, the inner surface of each coil 123 may be provided with a pair of slip rings d, e thereon to which opposed ends of the coil 123 are suitably connected, and which engage respective brushes ,1, g suitably secured to, but insulated from, the adjacent face of stator 115 and to which corresponding ends of conductors a, a-l are suitably connected.

In FIGURE 4, the hub 116 of driven rotor 117 is keyed to shaft 50, as at 125, and is also secured thereto by means of a set screw 12%. As heretofore stated, each pulley 102 is loosely mounted on shaft 50. In this instance, pullcy 192 is shown in FIGURE 4 as being rotatably mounted on shaft 50 by means of anti-friction bearings 130, 131. The pulley 102 of FIGURE 4 is prevented from having endwise movement relative to stator 115 and driven rotor 117 by a collar 132 fixed on shaft 59, as by means of a set screw 133, and which engages the inner race of the outer bearing. 130.

Theinner race of inner bearing 131 bears against a shoulder 134 formed on the inner surface of driven rotor 117. The hub of pulley 192 is encircled by an annular plate or driving rotor 135 which is suitably keyed to the hub of the corresponding pulley 192, as at 135. It should be noted that driving rotor 135 is positioned closely adjacent driven rotor 117 and coil 123 and may have limited axial movement relative thereto, such axial movement being limited by a suitable limiting ring 137 encircling the hub of the corresponding pulley 162 and being spaced outwardly from the corresponding end of driven rotor 117 and its coil 123.

From the foregoing, it is apparent that all the pulleys 102 and the shaft 59 may rotate relative to each other whenever corresponding coils 123 are not activated or energized. However, upon a corresponding coil 123 being energized, the corresponding driving rotor 135 is pulled tightly against driven rotor 117 and coil 123 so that the adjacent pulley 162 (which rotates continuously throughout operation of the machine) then transmits rotation to shaft 50 through the medium of the corresponding coil 123, driven rotor 117 and hub 116.

As heretofore stated, whenever one or more of the strands or slivers S1 through S8 is parted as it approaches the drafting mechanism, the speed of the front drafting rolls 14, 24 is decreased accordingly. Therefore, it is apparent that clutch 133 of transmission unit 95 must be deactivated and clutch 103 of transmission unit 96 must be activated upon any one of the strands S-1 through S-ti becoming parted and, further, upon an additional strand or sliver becoming parted, regardless of which. strand it might be, so that two strands are then parted at the same time, the clutches 103 of transmission units 95, 96 must be inoperative while the clutch 103 of transmission unit 97 is actuated.

It is to be noted that other similar transmission units, not shown, may function whenever three or more of the strands become parted, but the three transmission units 95, 96, 97 would probably be sufiicient for all practical purposes when taking into consideration the original number of strands or slivers being fed to the drafting mechanism and the extent to which the crown draft between the second and third pairs of drafting rolls 12, 22 and 13, 23 must be decreased as the number of slivers being fed to the drafting mechanism decreases.

In order to effect actuation of clutch 163 of transmission unit 96 whenever any one of the slivers S-1 through 8-8 becomes parted, and to effect actuation of clutch 1030f transmission unit 97 whenever any two of the slivers S-1 through SS becomes parted, a specialcontrol circuit is provided (FIGURE which is motivated by a suitable direct current power supply 144, in this instance. To this end, it will be observed in FIGURE 5 that each metallic segment 33 of bottom transverse contact bar 28 has one end of a resistor connected thereto, the resistors corresponding to sliver spoons;D-1 through D-S being respectively designated at R-1 through R-8. All the resistors R-1 through R-S are arranged in parallel relationship and are connected to a common conductor 140.

Each metallic segment 32 of upper transverse contact bar 27 has a corresponding conductor connected thereto, the conductors corresponding to the sliver spoons D1 through D-8 being respectively designated at W-l through W-S. The latter conductors are also arranged in parallel, and the ends thereof opposite from the metallic segments 32 are connected to a common conductor 141 to which one end of a conductor 142 is connected. The other end of conductor 142 is connected to a conductor or wire 143 extending from one side of the output of power supply 144. The other side of the output of said power supply 144 also has a conductor 146 leading therefrom to ground. The input of power supply 144 has conductors 150, 151 leading therefrom to the lead conductors 91, 92 heretofore described.

A conductor 152 extending from conductor has a conductor or wire 153 extending therefrom to one side ofthe coil 154 of a low-voltage relay 155. The other side of coil 154 is connected to ground by means of a conductor or wire 156. A normally open switch 157 of a suitable time-delay-relay 160 may be interposed in conductor 153, although the relay 160 and its switch 157 may not be required in all instances, as will be later explained. If switch 157 is not required in the particular installation of the control apparatus, it is apparent that conductor 153 may then extend directly to the coil 154 of low voltage relay without interruption. The end of conductor 152 opposite from conductor 140 is connected to one end of the coil 161 of time-delay-relay and the other end of coil 161 has a conductor 162 extending therefrom to ground. Low voltage relay 155 includes a normally open switch 163 which is closed upon energization of coil 154 and then establishes contact between a pair of conductors 164, 165.

Conductor 164 is connected to a medial portion of conductor 156 and is thus connected to ground. Conductor 165 is connected to one side of a double-throw switch 166 of a high voltage relay 167 which also includes a coil 170. When coil 1'70 is not energized or subjected to sufficiently high voltage, switch 166 norm-ally maintains contact between conductor 165 and a conductor 171 leading to a medial portion of a coil 172 of a relay 173. One end of coil 172 has the conductor 143 connected thereto and the other end of coil 172 has one end of a conductor 174 connected thereto and extending to high voltage relay 167. When relay 167 is activated, switch 166 breaks contact between conductors 165, 171 and makes contact between conductors 165, 174.

Coil of high voltage relay 167 has conductors 175, 176 connected to opposite ends thereof, conductor 175 being connected to ground. The end of conductor 176 opposite from coil 1701 is connected to a medial portion of conductor 153 at a point between switch 157 and coil 154 of low voltage relay 155.

Relay 173 is provided for controlling three parallel switches A, B, C which control energization of the clutches 103 of the respective transmission units 95, 96, 97. Switch A is normally closed and switches B, C are normally open. Although relay 173 may be of any desired construction, it is shown in the form of a solenoid having a solenoid plunger 181 to the free end of which switch A is suitably secured and which is normally urged to extended position by a tension spring 132.

Plunger 181 has a pair of longitudinally spaced switch actuators 183, 184 fixed thereon which are adapted to successively and independently engage and close the respective switches B, C so that, when only one half or a portion of coil 172 is energized, only switch B will be closed. On the other hand, when the entire length of the coil 172 is energized, plunger 181 is moved so that actuator 183 moves out of engagement with switch B and actuator 184 moves into engagement with switch C. When either actuator 183 or 184 closes the corresponding switch B or C, it is apparent that switch A is opened.

Corresponding sides of switches A, B, C have the ends of the respective conductors a, b, c opposite from clutches 103 of the respective transmission units 95, 96, 97 con- 9 nected thereto. The other sides of switches A, B, 6 have respective conductors or wires 185, 186, 187 con.- nected thereto. Conductor 185 leads from switch A to lead conductor 92 and the ends of conductors 186, 187 opposite from the respective switches B, C are connected to conductor 185.

In order that an attendant may quickly determine which of the three clutches 103 is energized, and thus determine whether one or more of the slivers S-l through 54% are parted and to determine the urgency of promptly piecing up any parted slivers, a suitable electrically operated warning device may be arranged to operate as each respective clutch is actuated. In this instance, the warning devices associated with the respective power trans.- mission units 95, 96, 97 are shown in the form of incandescent lamps 191, 192, 193 and may be of distinguishing colors. For example, the lamps 191, 192, 193 may be green, amber and red, respectively. a

In order that the lamps 191, 192, 193 may be energized only at such times as the clutches 103 of the respective transmission units 95, 96, 97 are energized, lamp 191 is interposed in a conductor 194 extending from lead conductor 92 to a medial portion of conductor a; lamp 192 is interposed in a conductor 195 extending from lead conductor 92 to the side of switch B opposite from conductor b; and lamp 193 is interposed in a conductor 196 extending from lead conductor 92 to that side of switch C opposite from conductor 0. The ends of conductors a-1, b-l, c-1 opposite from clutches 103 are connected to lead conductor 91.

Method of operation It is well known that many different types or blends of textile fibers are drafted through the drafting mech anisms of drawing frames, and the number of ends of sliver being fed to a drafting mechanism may vary from as few as 4 ends up to and exceeding 14 ends of sliver. Also the total draft to be produced in the slivers being drafted may vary considerably in accordance with the number of slivers being fed to the drafting mechanism and the characteristics of the slivers and the fibers of which they are formed. However, in order that the invention may be clearly understood, it is to be assumed, in this method of operation, that eight SO-grain cot-ton slivers are the desired number to be fed to the drafting mechanism and that a single SO-grain composite sliver is formed therefrom upon leaving the front drafting rolls 14, 24 thus indicating that there may be a draft of eight while all eight of the slivers S1 through SP8 are being properly fed to the back drafting rolls 11, 21.

It follows that, upon the parting of a single one of the slivers, a draft of seven would then be required between the back rolls 11, 21 and the front rolls 14, 24 in order to continue to produce a SO-grain sliver, and upon the parting of any two of the strands or slivers S1 through 8-8 a draft of six would be required between the back rolls 11, 21 and the front rolls 14, 24 in order to continue to produce a SO-grain sliver therefrom.

In the following example, it is to be assumed that all the bottom drafting rolls 1144 are of the same diameter and that the slivers S-l through S-8 are being fed to the back drafting rolls 11, 21 at a linear speed of approximately 100 feet per minute. It follows that, since the eight slivers S-l through S8 are being formed into a single sliver S of substantially the same size as eachof said eight slivers, the high peripheral speed imparted to the front drafting rolls 14, 24 while all the slivers S-1 through S-8 are being fed to the back drafting rolls 1 1, 21 would be approximately eight times that of the peripheral speed of the back drafting rolls 11, 21; i.e. 800 feet per minute. This speed would be reduced by approximately 100 feet per minute with the loss of one end and by approximately 200 feet per minute with the loss of two ends.

From the foregoing, it is apparent that the ratio between the speeds of pulley 82 and pulley 102 of transmission unit 95 should be approximately 8 to 1; the ratio between the speeds of pulley 82 and pulley 102 of transmission unit 96 should be approximately 7 to 1; and the ratio between the speeds of pulley 82 and pulley 102 of transmission unit 97 should be approximately 6 to 1. It may be assumed, therefore, that drive shaft is driven at a ratio relative to pulley 82 of approximately the square root of the aforementioned 8 to 1 ratio; i.e., 2.83 to 1. Thus, the ratio of the eifective diameter of pulley 100 to that of pulley 102 of transmission unit would be approximately 2.83 to 1, and the ratio of the effective diameter of pulley 82 to that of pulley 81 would also be approximately 2.83 to 1.

Since the relative speeds of the two drafting rolls 11, 12 and the relative speeds of the two drafting rolls 13, 14, and the draft effected thereby in the strands passing thereover, remains constant and it is necessary, in this example, to produce a total draft of seven whenever a single strand of the group S-1 through S-8 becomes parted, it follows that the ratio between pulleys 100, 102 of the intermediate speed transmission unit 96 is equal to seven divided by 2.83 or 2.47 to 1. In other words, the effective diameter of pulley'100 of transmission unit 96 would be approximately. 2.47 times larger than that of the corresponding pulley 102.

Since the slow speed power transmission unit 97 is actuated upon the absence of two of the slivers in the group 3-1 through S-8 being detected, it follows that the ratio between the pulleys 100, 102 of transmission unit 97 should be equal to six divided by 2.83 or 2.13 to 1. Thus, pulley of transmission unit 97 should be approximately 2.13 times larger than the corresponding pulley 182 in the present example. As heretofore stated, the peripheral speed of the calender rolls 40, 41 is preferably maintained at 1.04 times the peripheral speed of the front bottom drafting roll 14, regardless of the variations in the peripheral speed of the bottom drafting roll 14 effected by the present control apparatus. This insures that the composite sliver S formed from the strands S-l through S8 is maintained under tension at all times.

Once the desired speeds of the rear and front pairs of rolls 11, 21 and 14, 24 have been determined, the desired draft between adjacent pairs of drafting rolls need not be calculated to determine the sizes of the various pulleys 81, 82, 100, 102. However, in order that this example clearly illustrates the function of the drafting mechanism, an example of the ratios of the relative speeds of adjacent drafting rolls will now be given. One method commonly used for calculating such ratios includes determining the square root of the total draft and using the same as the ratio between the speeds of the bottom front roll 14 and the next adjacent or No. 2 bottom roll 13. The square root of two-and-one-half percent of the total draft serves as the ratio between the speeds of the bottom back drafting roll 11 and the No. 4 or next adjacent intermediate bottom roll 12. Thereafter, the ratio between the drafting rolls 13, 14 is multiplied by the ratio between the drafting rolls 11, 12 and the resulting product thereof is divided into the total draft number to determine the desired ratio between the two intermediate bottom drafting rolls 12, 13. This method of calculation of the drafting roll ratios results in approximately half the draft being effected between drafting rolls 11-13 and 21-23. 7

In the present example, in which an eight draft is to be effected in the eight slivers S.1 through S8 as they pass through the drafting mechanism, since the square root of eight is approximately 2.83, the ratio between the peripheral speeds of the front bottom drafting roll 14 and the No. 2 bottom drafting roll 13 is approximately 2.83 to 1. As heretofore stated, this is the assumed ratio between the effective diameters of pulleys 81, 82. Since the square root of two-and-one-half percent of eight is approximately l.42, it shall be assumed that the ratio between the peripheral speeds of the No. 3 bottom drafting 1 1 roll 12 and the rear bottom drafting roll 11 is approximately 1.45 to 1. Thus, the ratio between the peripheral speeds of the second and third bottom rolls 13, 12 is %=1.95 (approximately) This is in accord with the fact that the aforementioned ratio between the diameters of the two pulleys 100, 102 of high speed transmission unit 95 is approximately 2.83 to 1, since 1.45 l.95=2.83 (approximately).

In normal operation, in which all of the desired number of ends of sliver S-1 through S8 are being properly fed to the drafting mechanism, none of the sliver spoons or sensing elements D-1 through D-8 are in engagement with a corresponding segment 33 of the lower transverse contact bar 28 and, thus, the control circuit remains quiescent so that switch A is closed and current flows through the clutch 103 of high speed transmission 95 and through the warning device or lamp 191 associated therewith. Thus, in the present example, the power transmission unit 95 is active while the power transmission units 96, 97 are inactive and rotation is beng transmitted to the front bottom draftng roll 14 at a peripheral speed of approximately 800 feet per minute while the back bottom roll 11 is rotating at a peripheral speed of 100 feet per minute.

Before proceeding further with this description of the operation of the apparatus, exemplary values will be given to certain elements of the control circuit in FIG- URE 5. It is to be assumed that the power supply 144 converts the alternating current directed thereto through conductors 150, 151 to a 90 volt, 2 ampere, direct current and that each of the resistors R-l through R-8 has a resistance of ohms. It shall also be assumed that the coils 161, 154 of the relays 160, 155 will become operative to close the respective switches 157, 163 upon being subjected to an electrical impulse of approximately volts as well as any additional voltage to which they may be subjected. However, the coil 171) of relay 167 should be so wound that, although current may flow therethrough when coil 170 is subjected to an electrical impulse having a magnitude of less than volts, the magnetic flux produced by soil 170 will be insufficient to attract the armature or switch 166 thereto until the coil 170 is subjected to a minimum of 80 volts.

Upon the parting of any one of the slivers S-l through S-S permitting the corresponding sliver spoon to drop against a segment 33 of lower transverse bar 23, current flows from the power supply 144 at volts through conductors 142 and 141, through one of the conductors W-1 through W8, through the corresponding sensing element or sliver spoon and through one of the resistors R-1 through R-8. In this instance, it shall be assumed that strand S-4 has parted and, therefore, current will be flowing through resistor R-4.

Current flows from resistor R-4 through conductors 140, 152, through coil 161 of time-delay-relay and through conductor 162 to ground, thus energizing the coil 161 of time-delay-relay 16G. As heretofore stated, the coil 161 of relay 160 becomes active when a relatively low voltage of, say 70 volts, is applied thereto. According to Ohms law, since a single resistor R-4 is then active in the control circuit, the resistance of 10 ohms multiplied by two amperes of current elTects a voltage drop of 20 volts across resistor R4. When this 20 volts is subtracted from the 90 volts directed from the power supply 144, it follows that the voltage being applied in the control circuit is then 70 volts.

The time-delay-relay160 may be of any desired or conventional construction and, therefore, details thereof are omitted from the present disclosure. Time-delayrelay 160 may be of a type substantially as disclosed in FIGURE 18 of US. Patent No. 2,752,273 granted to George W. Mitchell on June 26, 1956, for example. In any event, time-delay-relay 160 should be of a type which will close switch 157 at a predetermined interval following the detection of the parted strand by a corresponding one of the sliver spoons S1 through S8 at the instant at which the trailing end of the parted strand reaches the nip of the rear drafting rolls 11, 21. As heretofore stated, since the slivers S-l through S8 are moving at a high rate of speed in their course to the drafting mechanism, the time-delay-relay 160 may be omitted in most instances.

In either event, current flows from conductor 152 through conductor 153, through the coil 154- of low voltage relay 155 and is grounded through conductor 156, thus closing switch 163 so that current fiows through approximately one-half of the coil 172 of relay 173. It is apparent that current flows through approximately onehalf of the coil 172 in this instance, because of the fact that current flows from conductor 143 through the upper portion of coil 172 in FIGURE 5, through conductor 171, switch 166, conductor 1165, switch 163 and conductors 164, 156 to ground. Although conductor 176 connects the coil of relay 167 to conductor 153 at this time, the low voltage of 70 volts applied to coil 170 is insufiicient to cause switch 166 to move downwardly in FIG- URE 5.

As heretofore stated, when the upper portion of coil 172 in FIGURE 5 is energized, this applies sufficient pulling force to plunger 181 only to open switch A and close switch B. Thus, the clutch 103 of transmission unit 95 is deenergized and the clutch 193 of transmission unit 96 is energized as current flows from lead conductor 91 through conductor 12-1, the coil of the latter clutch 103, the conductor b, switch B, conductors 186 and to lead conductor 92. The lamp 191 also becomes deenergized as lamp 192 becomes energized with the flow of current from conductor b through switch B and through conductor 195 and lamp 192 to the lead conductor 92.

It is thus seen that, upon the parting of any one of the slivers S-l through 8-?) while all the remaining slivers remain intact, transmission unit 95 is rendered inoperative as intermediate transmission unit 96 is rendered operative for driving the front rolls 14, 24 at an intermediate or slower speed than that at which they were driven by the transmission unit 95; Le, approximately 700 feet per minute in this example.

Now, upon any two of the slivers S1 through S-8 becoming parted so that two ends are down at the same time, two of the resistors R-l through R8 are rendered active in parallel in the control circuit. For purposes of description, it shall be assumed that the two slivers 8-4, 8-5 have become parted and the rear portions of the corresponding sliver spoons or sensing elements D-4, D-S have dropped into engagement with adjacent segments 33 of lower transverse bar 28. Thus, current will flow from the conductor 141 through both conductors W-4, W5 and through both resistors R-4, R5 to the conductor 14%.

Since, according to Ohms law, the voltage drop across two resistors in parallel is equal to the value of the two resistors in ohms multiplied by each other, divided by the value of the two resistors added together, and then multiplied by the amperes of current, the voltage drop across the two resistors R4, R5 would then be ten volts; that is This voltage drop of ten volts subtracted from the 90 volts at the power supply 144 results in 80 volts being applied to coils 161, 154, 170 of all three relays 160, 155, 167. Thus, both switches 157, 163 would again be closed in a manner heretofore described, or they would remain closed if one of the two ends had parted prior to the other end being parted.

Since the coil 170 of high voltage relay 167 will then have 80 volts applied thereto, the switch 166 would move downwardly in FIGURE 5 so the entire length of the 10 volts l3 coil '172 of relay 173 would then be energized. in this instance, it will be noted that conductor 174 is then connected to ground through switch 166, conductor 165, switch 163, and conductors 1 64, 156. p I

As heretofore stated, upon energization of the entire length of coil 172 of relay 173, the pulling force applied to plunger 181 by coil 172 move's plunger to where the switch C is closed as actuator 184 engages the same, and switches A, B are then opened. Thus, upon any two of the slivers S-l through S8 being parted, the two clutches 103 of transmission units 95, 96 are cleanergiz'ed as the clutch 133 of low speed transmission unit :97 is energized so that the front drafting rolls 14, 24 then rotate at a relatively slow speed which is approximately '600 feet per minutein this example. 7 v H I '7 Thus, the draft between the second and third pairs of rolls 13, 23 and 12, 22 is reduced so that the six remaining strands or slivers 8-1, 8-2, 8-3, S6, S-7 and 8-8 will be combined into a single sliver S of substantially the same weight as the previously formed sliver although, of course, the rate at which the sliver S would be delivered to the coiler can 45 would thenbe slower because the said six remaining slivers being fed to the drafting rolls ll, 21 would be moving at the same linear speed as they were when all the original number of slivers were being fed to the drafting mechanism or back drafting rolls 11, 21.

It is thus seen that the sliver spoons D-1 through D8 collectively form a measuring device whose indicating value varies only according to the number 'of strands passing therethrou'gh and wherein an electrical impulse is ob- :tained from said value and the magnitude of the impulse varies according to said value as effected through the medium of the resistors R-lthrough R-S. Thus, the

energy derived from such impulses is utilized to effect the drive of the front pair of drafting rolls 14, 24 at speeds corresponding to said impulse.

I, It is apparent, by referring to FIGURE 5, that lamp 192 is deenergize'd upon two strands being parted in their course to the drafting rolls 11, 21 and that lamp 193 is then energized. Since the manner in which current flows through the clutch 1G3 and lamp 193 of transmission unit 97 is quite similar to that described with respect to transmission unit 96, a further description thereof is deemed unnecessary.

U As heretofore stated, although additional power transmission units may be provided between shafts 80, 50 "so as to be rendered operative upont-he parting of three or more of the strands being fed to the drafting mechanism,

such an arrangement would not generally be required and Y t therefore, additional power transmission units are not shown in the present drawings.

It should be noted that, upon the parting of more than two strands in the embodiment iilustrated in FIGURES ,1 and 5, the control circuit would continue to operate in the same manner as that describedw'ith respect to the power transmission unit 97, since each time a resistor is rendered active in the controlcircuit in addition'to said 'two resistors, the voltage applied to the control circuit is increased due to the decrease in the voltage drop across the resistors. Thus, the warning lamp 193 would remain energized and, of course, whenever the warning lamp 193 is energized, theattendant should piece up any broken ends promptly. v v v It is not generally desirable to reduce the draft between the drafting rolls 13, 23 and 12, 22 beyondjthe extent to could then be stopped until'such time as at least all but ris n 14 two of the carding machines could be in simultaneous operation.

It is thus seen that I have provided a novel method for automatically controlling the weight per unit length of textile material issuing from a drafting mechanism and wherein the amount of draft imparted to the textile material by the drafting mechanism is automatically reduced in accordance with any reduction in the number of ends or slivers being fed thereto and also wherein the draft imparted to the textile material is increased upon restoration of such parted ends so that the inet-hodand the apparatus for carrying out the method is particularly adapted for use in a railway system in which the slivers are directed from a like number or plurality of carding machines in which the linear speed of the slivers may remain constant regardless of any reduction in the number of slivers being directed'to the drafting mechanism, and the resulting composite sliver formed from the group of slivers will continue to be of substantially uniform weight per unit length.

In the drawings and specification there has been set forth a preferred embodiment of the invention and, although specific terms are employed, they are used in a 'generic'and descriptive sense only and not for purposes of limitation, the scope of the invention being defined in the claims.

I claim:

1. A method of controlling a drafting mechanism having a series of pairs of drafting rolls including front, back and intermediate drafting rolls so as to produce a single 'sliver of substantially uniform weight from a group of a given number of slivers, which comprises (a) maintaining substantially constant the degree of draft imparted to said slivers at all times while all of said given number of slivers are being drafted,

- (b) sensing any variations in the number of slivers in said group relative to said given number during the drafting thereof and independently of variations'in the mass of the individual slivers, and

'(c) compensatively changing the degree of draftimparted to said slivers by the drafting mechanism solely in response to and in accordance with yariations in the number of said slivers so sensed relative to said given number during continued drafting to maintain the desired weight of sliver issuing from the drafting mechanism.

' 2. A method of controlling the angular speed of a front pair of drafting rolls in a series relative to a back pair of drafting rolls of constant angular speed to produce textile material of substantially uniform weight per unit length from a group of a given number of textile strands, said method comprising (a) driving said front pa'irof rolls 'at a given substantially constant highspeed at all times in which all the strands insaid group are passing through said back pair of rolls,

(b) detecting the absence of each of any of said strands in theircourse to at least one of said pairs of rolls,

(c producing an electrical impulse solely in response to the absence o'f'each strand so detected while varying the magnitude of such impulse solely according to the total number of strands whose absence is so detected, and V (d) reducing the angular speed of said front rolls solely "in response to the varying magnitude of said impulse tomaintain the desired weight of sliver issuing from the front drafting-rolls.

3. A method of controlling the angular speed of a front pair of drafting rolls in a series relative to a back pair of drafting rolls of constant angular speed to produce a textile material of substantially uniform weight per unit tially constant high speed'at all times during which all the strands in said group are passing through said back pair of rolls,

(b) detecting the absence of each of any of said strands in their course to at least one of said pairs of rolls,

(c) producing an electrical impulse in response to the absence of each strand so detected while varying the magnitude of such impulse according to the number of strands Whose absence is so detected,

(d) electrically reducing the angular speed of said front rolls in response to the production of said electrical impulse upon the absence of any one of said strands being so detected, and

(e) electrically reducing the angular speed of said front rolls in accordance with variation in the magnitude of said impulse effected by detection of the absence of at least one additional strand.

4. Apparatus for controlling a drafting mechanism having a series of pairs of drafting rolls including front, back and intermediate drafting rolls to produce a textile material of substantially uniform weight from a group of a given number of textile slivers, which comprises (a) means normally causing said mechanism to impart a substantially constant degree of draft to said slivers at all times during the drafing of all the slivers in said group,

(b) means for sensing the absence of any slivers in said group, and

(c) means operatively connected to at least one pair of said drafting rolls and to said sensing means and being responsive solely to and in accordance with the number of slivers whose absence is so sensed for compensatively reducing the degree of draft imparted to the remaining slivers by the drafting rolls to maintain the desired weight per unit length of the textile material issuing from the drafting mechanism.

5. Apparatus for controlling the angular speed of a front pair of drafting rolls in a series of drafting rolls relative to a back pair of rolls in said series to produce a textile material of substantially uniform weight per unit length from a group of textile strands, and wherein said back pair of drafting rolls are driven at a constant angular speed; said apparatus comprising (a) means for driving said pair of front rolls at a given substantially constant high speed at all times while all of the strands in said group are passing through said back pair of rolls,

(b) means for detecting the absence of each of any of said strands in their course to at least one of said pairs of rolls, and

() means operatively connected to said front roll driving means and to said detecting means and being responsive solely to and in accordance with the detection of the absence of at least one of any, but less than all, of said strands in said group for proportionally effecting a reduction in speed of said front pair of rolls.

6. Apparatus for controlling the angular speed of a front pair of drafting rolls in a series of drafting rolls relative to a back pair of drafting rolls in said series to produce textile material of substantially uniform weight per unit length from a group of textile strands wherein said back pair of drafting rolls is driven at a constant angular speed, said apparatus comprising (a) normally active means for driving said front pair of rolls at a given relatively high speed while all the strands in said group are passing through said pair of back rolls,

(b) means for detecting the absence of each of any of said strands in their course to at least one of said pairs of rolls,

(c) means operably connected to said detecting means for producing an electrical impulse in response to the absence of each strand so detected and for varying 16 the magnitude of such impulse according to the number of strands whose absence is so detected, and

((1) means operatively connected to said electrical impulse producing means for driving said front rolls at reduced angular speed in response to the varying magnitude of said impulse and in proportion to the number of strands remaining in said group with respect to the original number in said group while rendering inactive said normally active means.

7. Apparatus for controlling the angular speed of a front pair of drafting rolls in a series of drafting rolls relative to aback pair of drafting rolls in said series to produce a single textile sliver of substantially uniform weight per unit length from a group of textile slivers wherein said bacl; pair of drafting rolls is driven at a constant angular speed, said apparatus comprising (a) first normally active driving means for driving said front pair of rolls at a given relatively high speed while all the slivers in said group are passing through said pair of back rolls,

(b) means for detecting the absence of each of any of said slivers in said group in their course to at least one of said pairs of rolls,

(c) means operably connected to said detecting means for producing an electrical impulse in response to the absence of each sliver so detected and for varying the magnitude of such impulse according to the number of slivers whose absence is so detected,

((1) second driving means operatively connected to said electrical impulse producing means for driving said front rolls at reduced angular speed while rendering inactive said normally active means in response to the production of said electrical impulse upon the absence of any one of said strands being so detected, and

(e) third driving means operatively connected to said electrical impulse producing means for driving said front rolls at a further reduced angular speed in accordance with the variation in the magnitude of said impulse effected by detection of the absence of at least one additional sliver in said group and while rendering inactive said second driving means.

8. Apparatus for controlling the angular speed of a front pair of drafting rolls in a series of drafting rolls relative to a back. pair of drafting rolls to produce textile material of substantially uniform weight per unit length from a group of textile strands wherein said back pair of drafting rolls is driven at a constant angular speed, said apparatus comprising (a) normally active means for driving said front pair of rolls at a given relatively high speed while all the strands in said group are passing through said pair of back rolls;

(b) means for sensing the absence of each of any of said strands in their course to at least one of said pairs of rolls, and

(0) means operatively connected to said sensing means and being responsive to the number of strands whose absence is sensed for driving said front rolls at a proportionally slower speed while rendering inactive said normally active means.

9. Apparatus for controlling the angular speed of a front pair of drafting rolls in a series of drafting rolls relative to a back pair of drafting rolls to produce textile material of substantially uniform weight per unit length from a group of textile strands wherein said back pair of drafting rolls is driven at a constant angular speed, said apparatus comprising (a) a driven shaft,

(b) a normally active high speed transmission means coupling said shaft to said front rolls for driving said front pair of rolls at a given relatively high speed while all the strands in said group are passing through said pair of back rolls,

(c) at least one normally inactive transmission means l interposed between said shaft and said front rolls and being arranged, when active, to drive said front rolls at a predetermined slow speed relative to said high speed,

(d) means for detecting the absence of each of any of said strands in their course to at least one of said pairs of rolls, and

(e) means operatively connecting said detecting means to said normally active and normally inactive transmission means and being responsive to the detection of the absence of at least one of said strands by said detecting means for inactivating said normally active transmission means and activating said normally in- 7 active transmission means. Iii. Apparatus for controlling the angular speed of a front pair of drafting rolls in a series of drafting rolls relative to a back pair of dratfing rolls to produce textile material of substantially uniform weight per unit length from a group of textile strands wherein said back pair of drafting rolls is driven at a constant angular speed, said apparatus comprising (a) a constantly driven shaft,

(b) first normally active transmission means for transmitting rotation from said shaft to said front pair of rolls at a given relatively high speed While all the strands in said group are passing through said pair of back rolls,

(c) means for detecting the absence of each of any of said strands in their course to at least one of said pairs of rolls,

(d) a second normally inactive transmission means responsive to detection of the absence of any one of said strands by said detecting means for transmitting rotation from said shaft to said front pair of rolls at a slower speed relative to said high speed and substantially proportional to the number of remaining strands, and

(e) means operable automatically for rendering inactive said first transmission means whenever said second transmission means is transmitting rotation to said front pair of rolls.

11. A structure according to claim iii, including (f) a third normally inactive transmission means responsive to detection of the absence of any two of said strands for transmitting rotation from said shaft to said front pair of rolls at a still slower speed than that transmitted by said second transmission means and at a speed proportional to the number of strands then remaining, and

(g) said means operable automatically for rendering inactive said first transmission means also being operable to render inactive said second transmission means whenever said third transmission means is transmitting rotation to said front pair of rolls.

12. Apparatus for controlling the speed of a front pair of drafting rolls relative to a preceding pair of drafting rolls driven at a substantially constant'speed and to which a group of slivers is directed comprising (a) a sensing element for sensing the absence of each of any of said slivers,

(b) a continuously driven shaft,

(c) a second shaft drivingly connected to said front pair of rolls,

(d) a plurality of clutches, including first, second and third clutches, operatively connected to said second shaft, each clutch comprising (1) a driving member, (2) a driven member, and

(3) electrically operable means for coupling to gether said driving and driven members of each clutch for transmitting rotation therefrom to said second shaft,

(e) driving connections for transmitting rotation from said driven shaft to the driving members of said first, second and thirdclutches at respective high, intermediate and slow relative speeds,

(f) means normally activating said electrically operable means of only said first clutch,

(g) means responsive to one only of any of said sensing elements sensing the absence of a sliver for deactivating said electrically operable means of said first clutch and activating said electrically operable means of said second clutch, and

(h) said responsive means also being responsive to at least two of any of said sensing elements sensing the absence of respective slivers for effecting activation of the electrically operable means of said third clutch while rendering deactivated said first and second clutches.

13. Apparatus for controlling the speed of a front pair of drafting rolls relative to a preceding pair of drafting rolls driven at a substantially constant speed and to which a group of slivers is directed comprising (a) a sensing element for sensing the absence of each or any of said silvers,

(b) a continuously driven shaft,

(c) a second shaft drivingly connected to said front pair of rolls,

((1) a plurality of clutches, including first, second and third clutches, operatively connected to said second shaft, each clutch comprising (1) a driving member,

(2) a driven member, and

(3) means for coupling together said driving and driven members of each clutch for transmitting rotation therefrom to said second shaft,

(e) driving connections for transmitting rotation from said driven shaft to the driving members of said first, second and third clutches at respective high, intermediate and slow relative speeds,

(f) means normally activating said coupling means of only said first clutch,

(g) means responsive to one only of any of said sensing elements sensing the absence of a sliver for deactivatin the coupling means of said first clutch and activating the coupling means of said second clutch, and

(h) said responsive means being responsive to the sensing of the absence of more than one of the slivers by corresponding sensing elements for deactivating the coupling means of said second clutch and activating the coupling means of said third clutch.

References Qitedby the Examiner UNETED STATES PAT ENTS 2,749,573 6/1956 McAngus 19-24O 2,964,803 12/1960 Robinson 19-240 FOREIGN PATENTS 1,011,329 6/1927 Germany.

744,399 2/ 1956 Great Britain. 906,795 9/ 1962 Great Britain. 1,180,379 6/1959 France.

DOWALD W. PARKER, Primary Examiner. RUSSELL C. MADER, Examiner. 

1. A METHOD OF CONTROLLING A DRAFTING MECHANISM HAVING A SERIES OF PAIRS OF DRAFTING ROLLS INCLUDING FRONT, BACK AND INTERMEDIATE DRAFTING ROLLS SO AS TO PRODUCE A SINGLE SLIVER OF SUBSTANTIALLY UNIFORM WEIGHT FROM A GROUP OF A GIVEN NUMBER OF SLIVER, WHICH COMPRISES (A) MAINTAINING SUBSTANTIALLY CONSTANT THE DEGREE OF DRAFT IMPARTED TO SAID SLIVERS AT ALL TIMES WHILE ALL OF SAID GIVEN NUMBER OF SLIVERS ARE BEING DRAFTED, (B) SENSING ANY VARIATIONS IN THE NUMBER OF SLIVERS IN SAID GROUP RELATIVE TO SAID GIVEN NUMBER DURING THE DRAFTING THEREOF AND INDEPENDENTLY OF VARIATIONS IN THE MASS OF THE INDIVIDUAL SLIVERS, AND (C) COMPENSATIVELY CHANGING THE DEGREE OF DRAFT IMPARTED TO SAID SLIVERS BY THE DRAFTING MECHANISM SOLELY IN RESPONSE TO AND IN ACCORDANCE WITH VARIATIONS IN THE NUMBER OF SAID SLIVERS SO SENSED RELATIVE TO SAID GIVEN NUMBER DURING CONTINUED DRAFTING TO MAINTAIN THE DESIRED WEIGHT OF SLIVER ISSUING FROM THE DRAFTING MECHANISM.P 